Sorry to throw a spanner - my email server has been very tardy recently and I've just caught up with this discussion.

This looks to me more like a large skipper, going simply on the sex brand. I have two guides, one which has photos and the Collins with drawings. In both, the Lulworth sex brand is shown as thin and wavy while the Large skipper's sex brand is a broader gash like in this photo. I'm looking particularly at the third photo. Any thoughts?

You have pictured my assessment exactly: the large skipper undersides consistenly show a faint patterning, whereas the Lulworth skipper undersides are consistently plain.

Alan,

I know what you mean about the large skipper's sex brand, but to me the other markings make a clear distinction: the Lulworth skipper has a plainer darker border, whereas that of the large skipper is more mottled.

I understand your concern about the patterning but something is anomalous here. Either the sex brand is far to wide for the Lulworth or the underside is apparently too plain for the Large. I've made an extensive search on the Internet (butterfly sites only - flikr etc can hold loads of misidentified stuff) for a Lulworth with a broad sex brand as in the specimen under discussion and I couldn't find one. Maybe you can. So I searched instead for a large with a plain underside and found this: